The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a functional block diagram of an engine system 100 is presented. An engine 102 produces drive torque for a vehicle. In the illustrated example, an internal combustion engine is described, however, it should be noted that any torque producing device may be used, such as, but not limited to, an electric motor, diesel engine or turbine. Air is drawn into the engine 102 through an intake manifold 104. A throttle valve 106 varies the volume of air drawn into the intake manifold 104. Opening of the throttle valve 106 is controlled by an electronic throttle control (ETC) motor 107. The air mixes with fuel from one or more fuel injectors 108 to form an air and fuel (A/F) mixture.
The A/F mixture is combusted within one or more cylinders of the engine 102, such as cylinder 110. In various engine systems, such as the engine system 100, combustion is initiated by a spark provided by a spark plug 112. Exhaust resulting from combustion is expelled from the cylinders to an exhaust system 114. Combustion of the A/F mixture produces torque. The engine 102 may transfer torque to a transmission 116, which may transfer torque to one or more wheels of the vehicle.
A control module 130 controls, among other things, torque output by the engine 102 based on temperatures provided by one or more temperature sensors. The temperature sensors each measure a temperature and may be located at various locations throughout the engine system 100. For example only, the engine system 100 may include an engine coolant temperature (ECT) sensor 118, an intake air temperature (IAT) sensor 120, an oil temperature (OT) sensor 122, a transmission oil temperature sensor 124, and/or an ambient air temperature sensor (not shown).
In addition, the control module 130 receives a signal from a speed sensor (not shown) in order to determine if the vehicle is moving. Speed sensors have a number of limitations, including the inability to detect low speed movement of a vehicle, which is sometimes related to the sampling frequency of the sensor. Furthermore, speed sensors may be sensitive to noise at engine start-up or vibration during idle. This sensitivity results in the speed sensor indicating high speed movement even when the vehicle is stationary.